First off, this could be a 4.5 but the biggest 'problem'…

First off, this could be a 4.5 but the biggest 'problem' I have run into is that the mesh padding on the back, shoulder straps, and hip belt happens cause abrasion like a mofo on any clothing I've worn.

I have 3 pieces of great gear, a Railriders shirt that held up excellent for 1500+ continuous miles on the AT, an Arc'teyrx windpro fleece hoody, and a brand new Ice Breakers heavyweight wool layer, all get SERIOUS abrasion/pilling right on the top of the back, top of the chest, and lower back. It is a major flaw, unfortunately.

I put duct tape over the padding and it works without this issue. I will be using some seamgrip and putting a layer of smooth nylon over it as a longer term solution. However, this is kind of crazy in that wearing this pack for a week could easily ruin your favorite pieces of gear by rubbing them threadbare from just the regular jostling that occurs with moving around.

i like all other features a lot--two pockets on the lid are great--one for the items you don't need but want, the other for things like sunglasses. Backdoor access is fantastic and works well once you learn to pack an item or two there that you want quick access to (like lunch!). Hipbelt pocket holds gps or camera or snacks fine, and mesh side pockets hold water bottles, pickets, misc gear well.

Other than this mesh issue, I'd also add a compression strap on each side.. but the single one along the back does pretty well.